diff --git a/lib/compress/zstdmt_compress.c b/lib/compress/zstdmt_compress.c
index 0b91ad4ea..1baccf0fc 100644
--- a/lib/compress/zstdmt_compress.c
+++ b/lib/compress/zstdmt_compress.c
@@ -9,10 +9,6 @@
 
 
 /* ======   Tuning parameters   ====== */
-#ifndef ZSTDMT_SECTION_LOGSIZE_MIN
-#  define ZSTDMT_SECTION_LOGSIZE_MIN 20   /* minimum size for a full compression job (20==2^20==1 MB) */
-#endif
-
 #define ZSTDMT_NBTHREADS_MAX 128
 
 
@@ -285,6 +281,7 @@ struct ZSTDMT_CCtx_s {
     unsigned frameEnded;
     unsigned allJobsCompleted;
     unsigned long long frameContentSize;
+    size_t sectionSize;
     ZSTD_CDict* cdict;
     ZSTD_CStream* cstream;
     ZSTDMT_jobDescription jobs[1];   /* variable size (must lies at the end) */
@@ -304,6 +301,7 @@ ZSTDMT_CCtx *ZSTDMT_createCCtx(unsigned nbThreads)
     cctx->nbThreads = nbThreads;
     cctx->jobIDMask = nbJobs - 1;
     cctx->allJobsCompleted = 1;
+    cctx->sectionSize = 0;
     cctx->factory = POOL_create(nbThreads, 1);
     cctx->buffPool = ZSTDMT_createBufferPool(nbThreads);
     cctx->cctxPool = ZSTDMT_createCCtxPool(nbThreads);
@@ -356,6 +354,22 @@ size_t ZSTDMT_freeCCtx(ZSTDMT_CCtx* mtctx)
     return 0;
 }
 
+unsigned ZSTDMT_setMTCtxParameter(ZSTDMT_CCtx* mtctx, ZSDTMT_parameter parameter, unsigned value)
+{
+    switch(parameter)
+    {
+    case ZSTDMT_p_sectionSize :
+        mtctx->sectionSize = value;
+        return 0;
+    default :
+        return ERROR(compressionParameter_unsupported);
+    }
+}
+
+
+/* ------------------------------------------ */
+/* =====   Multi-threaded compression   ===== */
+/* ------------------------------------------ */
 
 size_t ZSTDMT_compressCCtx(ZSTDMT_CCtx* mtctx,
                            void* dst, size_t dstCapacity,
@@ -487,7 +501,8 @@ static size_t ZSTDMT_initCStream_internal(ZSTDMT_CCtx* zcs,
             if (zcs->cdict == NULL) return ERROR(memory_allocation);
     }   }
     zcs->frameContentSize = pledgedSrcSize;
-    zcs->targetSectionSize = (size_t)1 << MAX(ZSTDMT_SECTION_LOGSIZE_MIN, (zcs->params.cParams.windowLog + 2));
+    zcs->targetSectionSize = zcs->sectionSize ? zcs->sectionSize : (size_t)1 << (zcs->params.cParams.windowLog + 2);
+    zcs->targetSectionSize = MAX(ZSTDMT_SECTION_SIZE_MIN, zcs->targetSectionSize);
     zcs->inBuffSize = zcs->targetSectionSize + ((size_t)1 << zcs->params.cParams.windowLog);
     zcs->inBuff.buffer = ZSTDMT_getBuffer(zcs->buffPool, zcs->inBuffSize);
     if (zcs->inBuff.buffer.start == NULL) return ERROR(memory_allocation);
diff --git a/lib/compress/zstdmt_compress.h b/lib/compress/zstdmt_compress.h
index 84d25f738..c00782e9d 100644
--- a/lib/compress/zstdmt_compress.h
+++ b/lib/compress/zstdmt_compress.h
@@ -7,6 +7,10 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  */
 
+
+/* Note : All prototypes defined in this file shall be considered experimental.
+ *        There is no guarantee of API continuity (yet) on any of these prototypes */
+
 /* ===   Dependencies   === */
 #include <stddef.h>   /* size_t */
 #define ZSTD_STATIC_LINKING_ONLY   /* ZSTD_parameters */
@@ -27,12 +31,32 @@ ZSTDLIB_API size_t ZSTDMT_compressCCtx(ZSTDMT_CCtx* cctx,
 
 /* ===   Streaming functions   === */
 
-ZSTDLIB_API size_t ZSTDMT_initCStream(ZSTDMT_CCtx* zcs, int compressionLevel);
-ZSTDLIB_API size_t ZSTDMT_resetCStream(ZSTDMT_CCtx* zcs, unsigned long long pledgedSrcSize);    /**< pledgedSrcSize is optional and can be zero == unknown */
-ZSTDLIB_API size_t ZSTDMT_initCStream_advanced(ZSTDMT_CCtx* zcs, const void* dict, size_t dictSize,   /**< dict can be released after init, a local copy is preserved within zcs */
-                                   ZSTD_parameters params, unsigned long long pledgedSrcSize);  /**< pledgedSrcSize is optional and can be zero == unknown */
+ZSTDLIB_API size_t ZSTDMT_initCStream(ZSTDMT_CCtx* mtctx, int compressionLevel);
+ZSTDLIB_API size_t ZSTDMT_resetCStream(ZSTDMT_CCtx* mtctx, unsigned long long pledgedSrcSize);    /**< pledgedSrcSize is optional and can be zero == unknown */
 
-ZSTDLIB_API size_t ZSTDMT_compressStream(ZSTDMT_CCtx* zcs, ZSTD_outBuffer* output, ZSTD_inBuffer* input);
+ZSTDLIB_API size_t ZSTDMT_compressStream(ZSTDMT_CCtx* mtctx, ZSTD_outBuffer* output, ZSTD_inBuffer* input);
 
-ZSTDLIB_API size_t ZSTDMT_flushStream(ZSTDMT_CCtx* zcs, ZSTD_outBuffer* output);   /**< @return : 0 == all flushed; >0 : still some data to be flushed; or an error code (ZSTD_isError()) */
-ZSTDLIB_API size_t ZSTDMT_endStream(ZSTDMT_CCtx* zcs, ZSTD_outBuffer* output);     /**< @return : 0 == all flushed; >0 : still some data to be flushed; or an error code (ZSTD_isError()) */
+ZSTDLIB_API size_t ZSTDMT_flushStream(ZSTDMT_CCtx* mtctx, ZSTD_outBuffer* output);   /**< @return : 0 == all flushed; >0 : still some data to be flushed; or an error code (ZSTD_isError()) */
+ZSTDLIB_API size_t ZSTDMT_endStream(ZSTDMT_CCtx* mtctx, ZSTD_outBuffer* output);     /**< @return : 0 == all flushed; >0 : still some data to be flushed; or an error code (ZSTD_isError()) */
+
+
+/* ===   Advanced functions and parameters  === */
+
+#ifndef ZSTDMT_SECTION_SIZE_MIN
+#  define ZSTDMT_SECTION_SIZE_MIN (1U << 20)   /* 1 MB - Minimum size of each compression job */
+#endif
+
+ZSTDLIB_API size_t ZSTDMT_initCStream_advanced(ZSTDMT_CCtx* mtctx, const void* dict, size_t dictSize,  /**< dict can be released after init, a local copy is preserved within zcs */
+                                          ZSTD_parameters params, unsigned long long pledgedSrcSize);  /**< pledgedSrcSize is optional and can be zero == unknown */
+
+/* ZSDTMT_parameter :
+ * List of parameters that can be set using ZSTDMT_setMTCtxParameter() */
+typedef enum { ZSTDMT_p_sectionSize    /* size of input "section". Each section is compressed in parallel. 0 means default, which is dynamically determined within compression functions */
+    } ZSDTMT_parameter;
+
+/* ZSTDMT_setMTCtxParameter() :
+ * allow setting individual parameters, one at a time, among a list of enums defined in ZSTDMT_parameter.
+ * The function must be called typically after ZSTD_createCCtx().
+ * Parameters not explicitly reset by ZSTDMT_init*() remain the same in consecutive compression sessions.
+ * @return : 0, or an error code (which can be tested using ZSTD_isError()) */
+ZSTDLIB_API unsigned ZSTDMT_setMTCtxParameter(ZSTDMT_CCtx* mtctx, ZSDTMT_parameter parameter, unsigned value);
diff --git a/programs/fileio.c b/programs/fileio.c
index 3864a5fab..86db12acb 100644
--- a/programs/fileio.c
+++ b/programs/fileio.c
@@ -113,6 +113,16 @@ void FIO_setNbThreads(unsigned nbThreads) {
 #endif
     g_nbThreads = nbThreads;
 }
+static U32 g_blockSize = 0;
+void FIO_setBlockSize(unsigned blockSize) {
+    if (blockSize && g_nbThreads==1)
+        DISPLAYLEVEL(2, "Setting block size is useless in single-thread mode \n");
+#ifdef ZSTD_MULTITHREAD
+    if (blockSize-1 < ZSTDMT_SECTION_SIZE_MIN-1)   /* intentional underflow */
+        DISPLAYLEVEL(2, "Note : minimum block size is %u KB \n", (ZSTDMT_SECTION_SIZE_MIN>>10));
+#endif
+    g_blockSize = blockSize;
+}
 
 
 /*-*************************************
@@ -283,10 +293,12 @@ static cRess_t FIO_createCResources(const char* dictFileName, int cLevel,
             if (comprParams->strategy) params.cParams.strategy = (ZSTD_strategy)(comprParams->strategy - 1);
 #ifdef ZSTD_MULTITHREAD
             {   size_t const errorCode = ZSTDMT_initCStream_advanced(ress.cctx, dictBuffer, dictBuffSize, params, srcSize);
+                if (ZSTD_isError(errorCode)) EXM_THROW(33, "Error initializing CStream : %s", ZSTD_getErrorName(errorCode));
+                ZSTDMT_setMTCtxParameter(ress.cctx, ZSTDMT_p_sectionSize, g_blockSize);
 #else
             {   size_t const errorCode = ZSTD_initCStream_advanced(ress.cctx, dictBuffer, dictBuffSize, params, srcSize);
-#endif
                 if (ZSTD_isError(errorCode)) EXM_THROW(33, "Error initializing CStream : %s", ZSTD_getErrorName(errorCode));
+#endif
         }   }
         free(dictBuffer);
     }
diff --git a/programs/fileio.h b/programs/fileio.h
index 9ef449294..19f09c33a 100644
--- a/programs/fileio.h
+++ b/programs/fileio.h
@@ -41,6 +41,7 @@ void FIO_setChecksumFlag(unsigned checksumFlag);
 void FIO_setRemoveSrcFile(unsigned flag);
 void FIO_setMemLimit(unsigned memLimit);
 void FIO_setNbThreads(unsigned nbThreads);
+void FIO_setBlockSize(unsigned blockSize);
 
 
 /*-*************************************
diff --git a/programs/zstdcli.c b/programs/zstdcli.c
index 785ecedee..549dad01a 100644
--- a/programs/zstdcli.c
+++ b/programs/zstdcli.c
@@ -118,6 +118,7 @@ static int usage_advanced(const char* programName)
     DISPLAY( "--[no-]check : integrity check (default:enabled) \n");
 #ifdef ZSTD_MULTITHREAD
     DISPLAY( " -T#    : use # threads for compression (default:1) \n");
+    DISPLAY( " -B#    : select size of independent sections (default:0==automatic) \n");
 #endif
 #endif
 #ifndef ZSTD_NODECOMPRESS
@@ -625,6 +626,7 @@ int main(int argCount, const char* argv[])
     if (operation==zom_compress) {
 #ifndef ZSTD_NOCOMPRESS
         FIO_setNbThreads(nbThreads);
+        FIO_setBlockSize((U32)blockSize);
         if ((filenameIdx==1) && outFileName)
           operationResult = FIO_compressFilename(outFileName, filenameTable[0], dictFileName, cLevel, &compressionParams);
         else